iMac 27" with second monitor boots to black with cursor

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iMac 27" with second monitor boots to black with cursor

I can't seem to find another discussion quite like my particular "boot to black screen" problem:

New 27" iMac Retina 5K (Late 2015) running OS X El Capitan 10.11.3 with second Samsung monitor connected by Mini DP-DVI . When booting, both screens appear black, but the cursor is available and can be moved.

I must do a hard shutdown and disconnect the second monitor in order to boot to the login screen. Then I can reconnect the monitor and everything works.

Any suggestions for a fix?

iMac (Retina 5K, 27-inch, Late 2015), OS X El Capitan (10.11.3)

Posted on Feb 5, 2016 8:40 PM

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Answer 1

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burnhamish Author

Level 1

1 points

Feb 6, 2016 7:13 PM in response to burnhamish

So, I spent some time with Apple customer support. After several of the standard troubleshooting steps for Mystery Problems, they came to the conclusion that there was a driver incompatibility with the Samsung monitor at boot time that was mucking things up, and I would have to just accept booting with the second monitor disconnected, then reconnect it after a successful login.

Samsung does not write monitor drivers for Mac (for whatever reason), which is why customer support figures there was a hangup at booting. But why does OS X recognize the monitor and run it just fine otherwise? Why hang up only at boot time? And why does my 2007 Mac Book Pro running the same version of El Capitan boot just fine with the monitor connected? Does it have something to do with the Thunderbolt/mini-DP-to-DVI connection? I don't know, and I suppose Apple Support doesn't either. 😕

I stumbled upon a kludge, which is this:

1. Boot with the second monitor connected

2. At the "black screen with cursor" hold the power button long enough to put the computer to sleep

3. Wake up the computer with the keyboard or trackpad or whatever

4. Lo and behold the login screen appears.

5. Log in as usual.

6. 🙂

I hope this helps somebody. Someday I will get a more compatible monitor, and it won't be a Samsung.

They make nice TVs, though.

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Answer 2

Mar 31, 2016 9:06 AM in response to burnhamish

My late 2013 Mac Pro running Yosemite worked perfectly fine for over 1 yr with a 30" Cinema Display and 27" Samsung monitor w/ tv. The Samsung is connected via HDMI. I waited to upgrade to El Capitan (10.11.4) until recently. Concurrent with upgrade, insert everything burnhamish says above for boot and/or restart of my system.

I worked out of town for about a year with a Mac Book Pro and 2 of the 27" Samsung monitors/tvs. I think the period covered 2 of the mountain OSs. This configuration produced no black screen problems.

My black screen does come with the cursor in the upper left corner so the solution(s) for booting when this occurs also apply. The cursor may appear on primary or secondary screen (go figure).

For now I will remain satisfied that I can easily unplug the second monitor when booting, which always elevates BLACK SCREEN.

I just remembered I have an old Proscan tv/dvd player setting across the room. I'll plug it in, restart and be right back---same black screen problem.

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Answer 3

dalyaf

Level 1

4 points

Apr 7, 2016 1:42 AM in response to burnhamish

Hi,

This fix worked for me on a similar (and seemingly common) black screen with cursor top left problem with my new 27" 5K iMac. I dont have an additional monitor, though. I had been through this a couple of times on updating El Capitan, the first time being the day of purchase. Anyhow today after installing the latest El Capitan update, I had the same problem again. Did all of the usual things (PRAM etc), but nothing worked. Before going further, I had a cable for my iPhone 5s sticking out of a USB port and thought, what the heck. After plugging the keyboard into USB using the Lightning adapter, the login screen appeared. The Keyboard charge was fine though, so Im not sure why it didnt recognise it in the first place.

It seems that the system hung after restart and failed to display the login screen. Not sure of the reason why, but at least this allowed me to log in and complete the update.....and hopefully go back to booting up completely....

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Answer 4

Jun 17, 2016 11:21 AM in response to burnhamish

Having the same issue but with a 27" Dell UltraHD. Works on boot fine with my MacbookPro but not my new 5k iMac.

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